There's not much detail there, it's easy to speculate.
The intersection of two county roads. Paved or dirt? Open fields or woods? Was the stop sign obscured by brush or easily visible?
I almost wore a UTV on the front of my F-450 as they came screaming around the corner of an intersection swinging wide. The roads here are dirt, there are no stop signs and visibility is low due to woods and thick brush. The posted speed limit is 35.
The new 1000 Kawasaki Mules can do 60mph, mine can do 45. Put that in the hands of a young kid and you're asking for trouble. The implication here is that the driver was male and probably showing off for the two girls. Maybe, maybe not.
I restrict my grandkids from driving on the road without an adult. And it is legal here to drive on the roads but you must be 14 or older and UTVs are supposed to stay under 35mph. My land is undeveloped and I have trails, I encourage them to stay home.